University of Houston researchers have developed a new stretchable and transparent electrical conductor, bringing the potential for a fully foldable cell phone or a flat-screen television that can be folded and carried under your arm closer to reality.
hifeng Ren, a physicist at the University of Houston and principal investigator at the Texas Center for Superconductivity, said there long has been research on portable electronics that could be rolled up or otherwise easily transported. But a material that is transparent and has both the necessary flexibility and conductivity has proved elusive – some materials have two of the components, but until now, finding one with all three has remained difficult.
The researchers reported that gold nanomesh electrodes, produced by the novel grain boundary lithography, increase resistance only slightly, even at a strain of 160 percent, or after 1,000 cycles at a strain of 50 percent. The nanomesh, a network of fully interconnected gold nanowires, has good electrical conductivity and transparency, and has “ultrahigh stretchability,” according to the paper.
And unlike silver or copper, gold nanomesh does not easily oxidize, which Ren said causes a sharp drop in electrical conductivity in silver and copper nanowires.
Guo said the group is the first to create a material that is more stretchable and conductive at similar transparency, as well as the first to use grain boundary lithography in the quest to do so. More importantly, he said, it is the first to offer a clear mechanism to produce ultrahigh stretchability.
The grain boundary lithography involved a bilayer lift-off metallization process, which included an indium oxide mask layer and a silicon oxide sacrificial layer and offers good control over the dimensions of the mesh structure.